Orbit Basics
Semi-major axis, eccentricity, period, perigee/apogee velocity and energy from altitudes.
Sun-Synchronous Orbit
Required SSO inclination vs altitude from the J2 precession condition, with chart.
Repeat Ground Track
Ground-track shift per rev and the exact altitude for an R revs / D days repeat cycle.
J2 Perturbations
Secular nodal regression, perigee rotation, nodal period, critical-inclination & SSO checks.
Coverage & Swath
Swath width, footprint area, slant range and nadir angle from elevation or sensor FOV.
Beta Angle & Eclipse
Solar beta angle and eclipse duration per orbit, with a full-year J2-drift chart.
Orbit Lifetime
Drag decay integration, lifetime estimate, drag make-up Δv and the 25-year rule check.
Δv Budget
Hohmann transfer with combined plane change, pure inclination change and phasing Δv.
Walker Constellation
Walker delta i:T/P/F — plane spacing, phasing and a per-satellite element table.
Constants & Orbits
Earth & time constants plus a typical-orbit quick reference from VLEO to graveyard.